test_that("get_trud_api_key() throws error when API key is missing or invalid", {
  expect_error(
    withr::with_envvar(c("TRUD_API_KEY" = ""), get_trud_api_key()),
    class = "missing_api_key"
  )
})

test_that("validate_arg_item() throws error when item argument is not integer", {
  expect_error(validate_arg_item("1"), "Argument `item` must be an integer.")
})


test_that("validate_arg_directory() throws error for invalid directory arguments", {
  expect_error(
    validate_arg_directory(1),
    "Argument `directory` must be a string"
  )

  temp_dir <- withr::local_tempdir()
  expect_error(
    validate_arg_directory(file.path(temp_dir, "invaliddirectory")),
    "Argument `directory` must be a valid file path."
  )
})

test_that("trud_error_message() generates appropriate error messages for different HTTP status codes", {
  response_without_json_body <- httr2::response(
    status_code = 499,
    url = "https://example.com",
    method = "GET",
    headers = list(),
    body = raw()
  )

  expect_match(
    trud_error_message(response_without_json_body)[2],
    "Is the TRUD website down?"
  )

  example_response <- httr2::response(
    status_code = 200,
    url = "https://example.com",
    method = "GET",
    headers = list(),
    body = raw()
  )

  with_mocked_bindings(
    {
      status_400_result <- trud_error_message(example_response)

      expect_match(status_400_result, "invalid API key")
    },
    try_resp_body_json = function(...) {
      list(httpStatus = 400)
    }
  )

  with_mocked_bindings(
    {
      status_404_result <- trud_error_message(example_response)

      expect_match(
        status_404_result[1],
        "Either this item number does not exist, or you are not subscribed to it"
      )
    },
    try_resp_body_json = function(...) {
      list(httpStatus = 404)
    }
  )
})

test_that("req_user_agent_trud() uses default user agent when environment variable is not set", {
  req <- httr2::request("https://example.com")

  # Temporarily unset the environment variable
  withr::with_envvar(c("TRUD_USER_AGENT" = NA), {
    result_req <- req_user_agent_trud(req)
    expect_equal(
      result_req$options$useragent,
      "trud (http://github.com/ropensci/trud)"
    )
  })
})

test_that("req_user_agent_trud() uses custom user agent from environment variable", {
  req <- httr2::request("https://example.com")
  custom_agent <- "Custom Agent for Testing"

  withr::with_envvar(c("TRUD_USER_AGENT" = custom_agent), {
    result_req <- req_user_agent_trud(req)
    expect_equal(result_req$options$useragent, custom_agent)
  })
})